In recent years, considerable effort has been directed towards wheelchair design in an attempt to make them more portable, as well as lighter in weight. Typically, these wheelchairs are foldable or collapsible to enable portability for transportation purposes. The wheelchair frames are usually formed from high-strength, lightweight, tubular materials such as aircraft-grade aluminum or graphite composites. Moreover, many of the subcomponents are extendable and/or detachable. Leg rest assemblies, for example, are often movably and/or detachably mounted to the wheelchair frames for increased portability.
Some of these leg rest assemblies even provide elevational movement so that a footrest device, which support the user's feet, may be selectively oriented between a raised position and a lowered position. Typically, these leg rest assemblies include a mounting support member mounted to the wheelchair frame, a footrest support member having a footrest device mounted on the distal end thereof, and a pivotal joint coupling the mounting support member to the footrest support member. The pivotal joint axis, or leg rest pivotal axis, typically is horizontally oriented, which permits the footrest device to be raised or lowered relative to the mounting support member. These leg rest assemblies are particularly desirable because the extension of the user's knee and/or legs may be adjusted for therapeutic purposes or for comfort.
Structural limitations often prevent coincidental placement of the leg rest pivotal axis with the pivotal axis of the user's knee. Thus, depending on the location of the leg rest pivotal axis, the distance between the knee and the footrest device may be decreased as the footrest support member is pivotally moved to a raised position. Accordingly, upon pivotal movement of the footrest support member to an elevated position, the footrest device can jam or compress the user's feet, legs or knees. Typical patented, prior art, pivotally-elevated, leg rest assemblies may be found in U.S. Pat. Nos. 4,968,051 to Luo; 4,966,379 to Mulholland; 4,893,827 to Gay et al.; and 4,333,681 to Nelson.
This problem has been overcome by providing a footrest support member which is extendable along a longitudinal axis of the footrest support member when the support member is pivotally raised from the lowered position to the elevated position. Accordingly, as the footrest support member is pivotally moved from a lowered position to an elevated position, the distance between the footrest device and the pivotal joint axis is increased. Such wheelchair leg rest assemblies are disclosed in U.S. Pat. No. 5,033,793 to Quintile; and 4,486,048 to Meyer.
While such prior art, extendable, leg rest assemblies have been able to effectively eliminate jamming or cramping of the feet upon extended elevation, often other problems are inherent in the linkage assemblies employed which extend the footrest devices. These assemblies are often bulky and awkward to operate. Most current commercially available, extending, leg rest assemblies require additional linkages and mechanisms which are disposed adjacent to the mounting and footrest support members. These linkages are often exteriorly exposed which presents potential safety hazards for the user during operation.
The Quintile patent, for example, discloses a leg rest assembly which includes a mounting support member, a footrest support member, and cooperating gear members which permit pivotal movement. Further, an extendable strut, including a footrest device on one end, is mounted on the opposite end to the footrest support member. An exteriorly exposed linkage assembly, which is operably coupled between the gears and the extendable strut, extends the strut in reaction to the pivotal movement of between the cooperating gears. As the linkage assembly moves relative to the pivotally mounted footrest support member, there is the possibility that an accident may occur. A person of impaired physical ability could easily pinch their appendages and/or get their clothing caught in the linkage or mechanisms during pivoting. Moreover, the Quintile linkage assembly is inherently complex, does not provide smooth transitional extension of the strut and, most importantly, has an exposed linkage mechanism which can endanger the user.
Accordingly, it is an object of the present invention to provide an extendable leg rest assembly which provides extension of a footrest device when raised to an elevated position.
It is another object of the present invention to provide an extendable leg rest assembly which reduces the exposure to injuries during operation.
Still another object of the present invention is to provide an extendable leg rest assembly which facilitates portability of a wheelchair.
It is a further object of the present invention to provide an extendable leg rest assembly which is durable, compact, easy to maintain, has a minimum number of components, is easy to use by unskilled personnel, and is economical to manufacture.
The apparatus of the present invention has other objects and features of advantage which will be more readily apparent from the following description of the Best Mode of Carrying Out the Invention and the appended claims, when taken in conjunction with the accompanying drawing.